Apron drafter for textile system

ABSTRACT

An apron drafting means for controlling fibers in such a manner that the fibers may be drafted at a higher draft and are capable of being drawn from the apron drafting means with pressure on substantially their entire length and without breaking of the fibers.

United States Patent [191 Morrison et' al.

[ Aug. 14, 1973 APRON DRAFTER FOR TEXTILE SYSTEM [75] inventors: Elbert F. Morrison; Raymond D.

Joy, both of Clarksville, Va.

[73] Assignee: Burlington Industries, Inc.,

Greensboro, N.C.

[22] Filed: Apr. 20, 1971 [2!] Appl. No.: 135,587

Related US. Application Data [62] Division of Ser. No. 842,865, July 18, 1969, Pat. No.

[52] US. Cl. 19/244 [51] Int. Cl D9111 5/86 [58] Field of Search l9/244-256, 236, 19/258, 260, 261

[56] References Cited UNITED STATES PATENTS 1,973,581 9/1934 Stong et a] 19/261 X 2,027,212 l/l936 Truslow 3,078,519 2/1963 Angioletti FOREIGN PATENTS OR APPLICATIONS 945,436 12/1963 Great Britain 19/244 741,449 11/1943 Germany 19/252 Primary Examiner-Dorsey Newton Attorney-Cushman, Darby & Cushman [5 7] ABSTRACT An apron drafting means for controlling fibers in such a manner that the fibers may be drafted at a higher draft and are capable of being drawn from the apron drafting means with pressure on substantially their entire length and without breaking of the fibers.

7 Claims, 6 Drawing Figures je l APRON DRAFTER FOR TEXTILE SYSTEM This application is a division of our copending application Ser. No. 842,865 filed July 18, 1969, now U.S. Pat. No. 3,609,836.

The present invention is an improvement in a textile system for drafting webs of cut fibers to produce a homogeneous sliver having randomized fibers with little or no turnbaeks. More particularly, the present inven' tion relates to an in-line apparatus which debonds, combs and/or drafts a web of fibers by a gilling type operation, then condenses the web and further drafts the web by an improved apron drafting means and straight ens the tail end of fibers to make the same more parallel to each other thereby producing a high quality homogeneous sliver capable of being coiled or subjected to a further textile operation.

In our copending Application Ser. No. 686,141, filed Nov. 28, 1967, now U.S. Pat. No. 3,522,634, issued, Aug. 4, 1970, there is disclosed a system of converting continuous filament tow into sliver by subjecting the tow to a cutting operation and then debonding, straightening, and randomizing operations while drafting, the system utilizing an in-line series of pin or gill drafting means which progressively operate on the web of fibers, the web being condensed between the various operations. While such a system has proved immensely successful over the system known in the trade as the Pacific Converter" as disclosed in U.S. Pat. Nos. 2,438,469, Mar. 23, 1948, and 2,706,834, Apr. 26, 1955, both issued to Robert C. Wilke, it has been found that the system of the present invention, when used in a Pacific Converter type of system obviates many of the difficulties encountered and produces a homogeneous sliver in increased amounts and of a higher quallty.

When utilizing a pin or gill drafting apparatus for delivering the fibers to a subsequent apparatus, any crossed fibers with ends entangled around the pins were broken or snarled when drawn out of the pins. If any of the pins were bent at their sharp pointed tips, their tips, upon entering the web, tangle with the fibers and fishhooked them on leaving causing broken fibers along with nips and pinpoints. While some pin or gill drafting is necessary, the present invention avoids the aforementioned difficulties by utilizing apron drafting means for a final drafting action as well as a final straightening action, thereby producing a higher quality sliver at a morerapid rate.

Additionally, another problem involved in the use of pin or gill drafting means is that the speed of operation is limited at which the pin or faller bars can enter, transport and leave the mass of fibers without the fibers following the pins and causing more tangles and tumbacks of the number of fibers at the upper and lower sides of the sliver. Since it is necessary to have some pin or gill drafting, production can be increased by utilizing apron drafting means after the pin or gill drafting operation as the apron drafting means can operate on the condensed web of fibers at much higher speeds thus, for example, delivering sliver to a coiling apparatus at the coiling apparatuss maximum capacity. While a modified type of Pacific Converter" such as disclosed in our afore-mentioned Application Ser. No. 686,141 can produce a sliver of about 85 pounds per hour when using a series of gilling stations and about 125 pounds per hour when using a series of gilling stations having a chain head drive for the faller bars, the system of the present invention has materially increased production of the sliver to about pounds per hour by utilizing, in its final finishing operation, apron drafting means which deliver the sliver to the next textile operation such as coiling. Additionaly, the sliver produced by the present invention is found to be of higher quality with less nips, pinpoints, and turnbacks and with practically no breakage. The evenness of the sliver was improved over 50 percent.

Although the present invention will be described in connection with a converter process, it is equally applicable to use on webs of cut fibers or on webs having blends of fibers such as wool and Dacron. It may even be used on webs of high tangle fibers such as wool and the like.

An object of the present invention is to provide an improved textile system for debonding, straightening and drawing fibers to produce a homogeneous sliver of uniform size with the fibers therein being uniformly randomized throughout the sliver.

Ancillary to the preceding object, it is a further object of the present invention to provide an in-line apparatus including gill or pin drafting means for preliminary drafting the fibers of a web while debonding and combing the fibers into parallel relationship, then condensing the web and further drafting and straightening the fibers by utilizing apron drafting means.

A still further object of the present invention is to provide an improved apron drafting means which automatically provides for compensation in input weight changes of the web without requiring adjustment to the apron drafting means, thereby increasing the uniformity of the sliver produced with fiber breakage substantially negligible.

Ancillary to the immediately preceding object, it is a further object of the present invention to provide an apron drafting means which will improve the control on the fibers passing therethrough and which will exert a pull on the fibers for their entire length from between the aprons to cause a straightening and a paralleling of fibers, thus, producing a better sliver.

These and other objects and advantages of the present invention will appear more fully in the following specification, claims and drawings in which:

FIG. 11 is a diagrammatic side elevational view of a textile system incorporating the in-line apparatus of the present invention;

FIG. 2 is an enlarged fragmentary view taken substantially on the line 2-2 of FIG. 11, the view illustrating the front rolls for the aprons of the apron drafting means of the present invention;

FIGS. 2A and 2B are views similar to FIG. 2 but on a reduced scale and showing a modification of the front rolls for the aprons of the apron drafting means;

FIG. 3 is an enlarged fragmentary diagrammatic perspective view of the apron drafting means and crimping means of the system of FIG. I; and

FIG. 4 is a schematic view illustrating in plan the sequential textile treatment of the web in forming the sliver.

Referring now to the drawings wherein like character or reference numerals represent like or similar parts, and in particular to FIG. 1, the apparatus of the present invention is disclosed in a converting system for converting continuous filament tow or the like into sliver. While the apparatus is disclosed in a converter system, it will be understood that the apparatus may be used in other textile operations such as spinning, twisting or the like, wherein a web of fibers must be first debonded, straightened, and drafted into a uniform sliver.

As shown in FIG. 1, two flat webs l and 12 of continuous filament tow are fed from a creel (not shown) through respective pairs of feed-in rolls l4 and 16 to cutter means 18 and 20. The cutter means 18 and 20 each include a cutter roll having one or more steel helical lands thereon and a cooperating metal anvil roll as fully disclosed in our aforementioned Application Ser. No. 686,141. The cutter means 18 and 20 are arranged with respect to each other so that the two webs l0 and 12, when superimposed on one another after cutting, have cut lines that appear as a diamond-shaped cutting pattern in plan profile. This provides for a better shingling of the fibers of the super-imposed webs l0 and 12 which will hereinafter be identified as a single web W.

The web W, which is brought together from the superimposed webs l0 and 12, is received in a stationary condensing station A to reduce the width of the web W to a predetermined size for entering the pin or gill drafting station B. The stationary condensing station A is a metal pan 22 having a flat bottom and side walls which converge in the direction of the movement of the web W sliding therethrough, the pan 22 discharging the web into the nip area of the backdraft section C of the pin or gill station E.

The pin or gill drafting station B includes the aforementioned backdraft station C, a pin station D, and a forward draft station F. The backdraft station C is comprised of an upper pressure roll 24 spring urged by spring means 26 toward a pair of splined or fluted rolls 32 and 34 closely positioned adjacent one another and adjacent the inlet of the pin station D. The rolls 32 and 34 are provided with pinion or gear belt pulleys 33 and 35 at the ends of the same, about which gear belts 28 pass, the gear belts being further entrained about pinion or gear belt pulleys 30. Suitable means are provided to drive the pulleys 30 and to adjust the speed of the same to a desired speed relative to the speed of the pin drafting means D.

While the back drafting station C has been disclosed as utilizing a pair of positively driven fluted rolls 32 and 34 for cooperating with the roll 24, an apron arrangement such as disclosed in our copending application Ser. No. 686,141 may be used.

The pin station D includes the usual upper and lower faller bars 36 having opposed pins for extending into the web W and then being drawn through the web W as the web is advanced therethrough, the faller bars moving in the same direction as the web but at a faster linear speed than the surface speed of the web as the web passes between the rolls 32 and 34 and the roll 24. Consequently, there is a drafting action on the fibers as the fibers enter the pin station D, the pins of the faller bars also causing the fibers to debond where necessary, straighten, and/or randomize. The front drafting station F of the pin or gill drafting station B includes an upper roll 38 spring urged by spring means 40 toward a pair of lower drive rolls 42 and 44. The rolls 42 and 44, which are both fluted, have a faster surface speed than the speed of the faller bars 36 so that when the forward ends of the fibers pass between the nip of the rolls 38, 42, and 44, the fibers are pulled from between the needles of the faller bars 36 to provide a second drafting action at station B and also to cause the faller bars to act now as a comb in reverse by straightening of the back end of any fibers having curlups.

The web W then enters a second condensing station G which is similar in construction to the condensing station A but further condenses the web W to a proper width for entering the apron drafting means H.

The apron drafting means H is best shown in FIGS. 1 and 3 and includes a back draft station I, a front draft station J, and apron means K intermediate the back draft and front draft stations. The back draft station l includes an upper pressure roll 46 spring urged by spring means 48 towards a lower drive roll 50, the drive roll operating at a surface speed higher than the surface speed of the drive rolls 42 and 44. The apron means K include an upper endless apron 52 entrained about a pair of horizontally spaced spring urged back and front rolls 54 and 56, respectively, and an idler or apron tightener roll 58. A lower apron 60 is entrained about horizontally spaced back and front drive rolls 62 and 64 as well as an apron tightener roll 66. The horizontal reaches of the aprons 52 and 60 oppose one another and have linear speed in a direction from left to right of FIG. 1 faster than the surface speed of the rolls 48 and 50 and consequently, the fibers of the web W passing through the nip of the rolls 48 and 50 is drafted therefrom as it passes into the area between the horizontal reaches of the aprons. The front draft station J of the apron drafting means H includes an upper pressure roll 68 spring urged by spring means 69 toward a drive roll 70, the drive roll 70 operating at an increased surface speed over the linear speed of the aprons so as to provide a further final drafting of the fibers of the web W. Both of the rolls 50 and 70 are fluted or splined steel rolls whereas their cooperating pressure rolls 46 and 68 respectively, are rubber covered rolls on steel arbors. By having the rolls 68 and 70 operating at an increased speed over the linear speed of the aprons, the fibers of the web as they pass between the nip of the rolls 68 and 70 are pulled almost their entire length from between the aprons causing a final straightening and paralleling of the fibers so as to make a better sliver.

Referring now to FIG. 2, it will be noted that the front apron pressure roll 56 is provided with a soft rubber covering having a 25 to 35 shore hardness. The length of this roll is greater than the width of the aprons 52 and 60 so that its end portions extend beyond the edges of the aprons. The front apron dn've roll 64 is of the same length as the roll 56, this roll being made of steel and having a center portion undercut on its periphery as indicated at 72. The center portion 72 has an axial extent less than the width of the apron. Outwardly of the undercut portion 72 of the roll 64, intermediate portions 74 and 76 are provided which are of a greater diameter than the diameter of the center portion 72. The intermediate portions 74 and 76 define with end portions 78 and 80 oppositely disposed flanges 82 and 84 spaced apart a distance equal to the width of the aprons, the flanges providing a guide for the edges of the aprons 60 and 52. The end portions of the roll 56 are each provided with a metal band 86, preferably of steel about the periphery thereof which engages the periphery of the end portions 78 and 80 so that the upper apron is driven thereby.

By providing the recessed or undercut portion 72 on the roll 64 along with the intermediate portion 74 and 76, and having these cooperate with the soft rubber cover of the roll 56, a gentle pressure is provided by the upper apron 52 on the web W which causes just'the right amount of friction between the fibers and the aprons as the web is being pulled or drafted by the rolls 68 and 70. Such an arrangement allows the apron drafting means H to compensate for input weight changes in the web W automatically without adjustments to the pressure rolls 54 and 56 or to the speed of the aprons. This results in the production of a sliver 50 percent more even than heretofore (28 percent versus 52 percent average) produced with little or no breakage of fibers (comparison made with apparatus such as that disclosed in our aforementioned copending application Ser. No. 686,14l).

As an alternative of the arrangement just previously described, an arrangement such as shown in FIG. 2A may be utilized as the front rolls of the upper and lower aprons. In more detail, the front roll 56 for the upper apron 52 is identical to the front roll 64' of the lower apron 60. Both rolls 56 and 64' are made of steel and provided with a center portion 72' undercut and of less axial extent than the width of the aprons. Outwardly of this portion 72' of each roll are intermediate portions 74' and 76' of greater diameter than the center portion and these intermediate portions define with the end portions 78 and 80 flanges which assist the tracking of both aprons.

When a very light-weight sliver is being processed, good control may be maintained between the aprons 52 and 60, by utilizing two soft rubber cotted front rolls 56" and 64" as shown in FIG. 2B. The rolls 56" and 64" may be provided with a metal band 86 about the periphery of the end portions thereof, the bands 86 of one roll engaging the bands 86 of the other roll to drive the same and to provide a means for making the aprons track.

While the above combination of rolls have been described for the front rolls of the upper and lower aprons, it will be appreciated that they may be utilized for the back rolls of the aprons when it is necessary to draft delicate fibers at a high rate. a

After the web passes between the nip of the rolls 68 and 70, it is again condensed by a slide pan 90 which feeds the web between the nip of a pair of crimper rolls 92 and 94, respectively. The upper crimper roll 92 is spring urged toward the lower drive roll 94. The roll 94 is driven at a surface speed faster than the surface speed of the roll 70 and it pushes the fibers of the web W into a stuffing box 96 which is U-shaped in crosssection and includes a bottom wall 98, side walls 100 and 102 and a pivoted elongated tongue member 104. The tongue 104 is pivoted at its upstream end as indicated at 106 adjacent the crimper rolls 92 and 94. The downstream end of tongue member 104 is weighted as is indicated at 108 so that it bears upon the top of the web W. The tongue member 104 holds the web back in the stuffing box 96 until the same is forced out of the box by the web entering from between the rolls 92 and 94, this action putting a short frequency crimp back into the fibers of the web thus causing the fibers in the web to adhere to one another better for the next process and handling. As shown in FIGS. 1 and 3, the web is delivered as a sliver to a coiling head 110.

As shown diagrammatically in FIG. 1, a motor M through suitable transmission devices progressively drives all of the lower rolls and the faller bars 36 at progressive increasing speeds throughout the apparatus from left to right. The use of the apron drafting means H enables the overall speed of operation of the system to be materially increased as the system is not limited by the maximum linear speed of faller bars at the discharge end of the same.

A source of vacuum V having suitable conduits N leading to discriminantly positioned suction head S is provided for removing the waste from the web W such as fish food or the like. This results in the sliver produce being free of waste and thus capable of use in making a high quality yarn.

The terminology used in this application is for the purpose of description and not limitation, the spirit and scope of the invention being defined in the claims.

What is claimed is:

1. An apron drafter for drafting a web of fibers into a homogeneous sliver comprising:

1. a pair of back rolls defining a nip for receiving the web, said rolls conveying the web at a predetermined linear speed;

2. an upper apron and a lower apron having cooperating reaches between which the web is fed from said back rolls, said upper apron and said lower apron respectively passing about at least a pair of upper horizontally spaced rear and front rolls and a pair of lower horizontally spaced rear and front rolls, and said aprons conveying the web at a predetermined linear speed faster than the linear speed of the web passing between said pair of back rolls, said front roll of the upper pair of horizontally spaced rolls having a soft rubber cover, and in which said front roll of said lower pair of said horizontally spaced rolls having an under-cut center portion on its periphery into which the lower apron may be depressed by the web, and said rubber cover of said upper front roll compensating for weight changes in the web passing between the aprons to allow for depression of the upper and lower aprons without adjustment for weight changes, said front roll of each pair of horizontally spaced rolls having a length greater than the width of the upper and lower aprons and in which the front roll of the upper pair of horizontally spaced rolls is driven by contact of its end portions extending beyond the web with end portions of the front roll of the lower pair of horizontally spaced rolls, said front roll of the upper pair of horizontally spaced rolls and said front roll of said lower pair of horizontally spaced rolls including means to cause said upper and lower aprons to track;

3. a pair of front ro'lls defining a nip for receiving the web discharged from between the upper and lower aprons, said pair of front rolls conveying the web at a faster linear speed than said pair of aprons so that fibers are pulled almost their entire length from between the aprons to straighten and parallel the same without twist and breakage.

2. An apron drafter-as claimed in claim I, in which said rubber cover has a shore hardness in the order of 25 to 35.

3. An apron drafter as claimed in claim ll, in which the front roll of the lower pair of horizontally spaced rolls is provided outwardly of its under-cut center portion with oppositely disposed intermediate portions having a diameter larger than said center portion and in which the end portions of the same have a diameter larger than the intermediate portions to define oppositely disposed flanges for providing a guide for the edges of said aprons.

4. An apron drafter as claimed in claim 1, in which the end portions of the front roll of the upper pair of horizontally spaced rolls is provided with a metal band about the periphery of the rubber cover for making contact with the front roll of the lower pair of horizontally spaced rolls. l

5. An apron drafter as claimed in claim 1, i: 'cluding crimping means for receiving the web discharged from the nip of said pair of front rolls, said crimping means comprising a pair of crimper rolls defining a nip therebetween and a stuffing box for receiving the web from the crimper rolls and discharging the same for coiling, said crimper rolls conveying the web at a linear speed faster than said pair of front rolls.

6. An apron drafter as claimed in claim 5, in which said stuffing box includes a U-shaped channel member having side walls and a bottom wall and being opened at both ends, and an elongated tongue pivoted to the side walls at the upstream end thereof and having its free end bearing upon the web at the downstream end, said tongue being weighted at its downstream end whereby discharge of the web therefrom depends on force of the web entering the stuffing box by said pair of crimper-rolls.

7. An apron drafter for drafting a web of fibers into a homogeneous sliver comprising:

1. a pair of back rolls defining a nip for receiving the web, said rolls conveying the web at a predetermined linear speed; 2. an upper apron and a lower apron having cooperating reaches between which the web is fed from said back rolls, said upper apron and said lower apron respectively passing about at least a pair of upper horizontally spaced rear and front rolls and a pair of lower horizontally spaced rear and front rolls, and said aprons conveying the web at a predetermined linear speed faster than the linear speed of the web passing between said pair of back rolls, said front rolls for both the upper and lower aprons being soft rubber covered cot rolls having a length wider than the width of the apron, each of the front rolls being provided with steel bands on the periphery of each of the end portions for contacting the end portions of the cooperating roll to drive the same and for causing the aprons to track,

said front roll of the upper pair of horizontally spaced rolls and said front roll of said lower pair of horizontally spaced rolls including means to cause said upper and lower aprons to track;

3. a pair of front rolls defining a nip for receiving the web discharged from between the upper and lower aprons, said pair of front rolls conveying the web at a faster linear speed than said pair of aprons so that fibers are pulled almost their entire length from between the aprons to straighten and parallel the same without twist and breakage. 

1. An apron drafter for drafting a web of fibers into a homogeneous sliver comprising:
 1. a pair of back rolls defining a nip for receiving the web, said rolls conveying the web at a predetermined linear speed;
 2. an upper apron and a lower apron having cooperating reaches between which the web is fed from said back rolls, said upper apron and said lower apron respectively passing about at least a pair of upper horizontally spaced rear and front rolls and a pair of lower horizontally spaced rear and front rolls, and said apronS conveying the web at a predetermined linear speed faster than the linear speed of the web passing between said pair of back rolls, said front roll of the upper pair of horizontally spaced rolls having a soft rubber cover, and in which said front roll of said lower pair of said horizontally spaced rolls having an under-cut center portion on its periphery into which the lower apron may be depressed by the web, and said rubber cover of said upper front roll compensating for weight changes in the web passing between the aprons to allow for depression of the upper and lower aprons without adjustment for weight changes, said front roll of each pair of horizontally spaced rolls having a length greater than the width of the upper and lower aprons and in which the front roll of the upper pair of horizontally spaced rolls is driven by contact of its end portions extending beyond the web with end portions of the front roll of the lower pair of horizontally spaced rolls, said front roll of the upper pair of horizontally spaced rolls and said front roll of said lower pair of horizontally spaced rolls including means to cause said upper and lower aprons to track;
 3. a pair of front rolls defining a nip for receiving the web discharged from between the upper and lower aprons, said pair of front rolls conveying the web at a faster linear speed than said pair of aprons so that fibers are pulled almost their entire length from between the aprons to straighten and parallel the same without twist and breakage.
 2. an upper apron and a lower apron having cooperating reaches between which the web is fed from said back rolls, said upper apron and said lower apron respectively passing about at least a pair of upper horizontally spaced rear and front rolls and a pair of lower horizontally spaced rear and front rolls, and said apronS conveying the web at a predetermined linear speed faster than the linear speed of the web passing between said pair of back rolls, said front roll of the upper pair of horizontally spaced rolls having a soft rubber cover, and in which said front roll of said lower pair of said horizontally spaced rolls having an under-cut center portion on its periphery into which the lower apron may be depressed by the web, and said rubber cover of said upper front roll compensating for weight changes in the web passing between the aprons to allow for depression of the upper and lower aprons without adjustment for weight changes, said front roll of each pair of horizontally spaced rolls having a length greater than the width of the upper and lower aprons and in which the front roll of the upper pair of horizontally spaced rolls is driven by contact of its end portions extending beyond the web with end portions of the front roll of the lower pair of horizontally spaced rolls, said front roll of the upper pair of horizontally spaced rolls and said front roll of said lower pair of horizontally spaced rolls including means to cause said upper and lower aprons to track;
 2. An apron drafter as claimed in claim 1, in which said rubber cover has a shore hardness in the order of 25 to
 35. 2. an upper apron and a lower apron having cooperating reaches between which the web is fed from said back rolls, said upper apron and said lower apron respectively passing about at least a pair of upper horizontally spaced rear and front rolls and a pair of lower horizontally spaced rear and front rolls, and said aprons conveying the web at a predetermined linear speed faster than the linear speed of the web passing between said pair of back rolls, said front rolLs for both the upper and lower aprons being soft rubber covered cot rolls having a length wider than the width of the apron, each of the front rolls being provided with steel bands on the periphery of each of the end portions for contacting the end portions of the cooperating roll to drive the same and for causing the aprons to track, said front roll of the upper pair of horizontally spaced rolls and said front roll of said lower pair of horizontally spaced rolls including means to cause said upper and lower aprons to track;
 3. a pair of front rolls defining a nip for receiving the web discharged from between the upper and lower aprons, said pair of front rolls conveying the web at a faster linear speed than said pair of aprons so that fibers are pulled almost their entire length from between the aprons to straighten and parallel the same without twist and breakage.
 3. a pair of front rolls defining a nip for receiving the web discharged from between the upper and lower aprons, said pair of front rolls conveying the web at a faster linear speed than said pair of aprons so that fibers are pulled almost their entire length from between the aprons to straighten and parallel the same without twist and breakage.
 3. An apron drafter as claimed in claim 1, in which the front roll of the lower pair of horizontally spaced rolls is provided outwardly of its under-cut center portion with oppositely disposed intermediate portions having a diameter larger than said center portion and in which the end portions of the same have a diameter larger than the intermediate portions to define oppositely disposed flanges for providing a guide for the edges of said aprons.
 4. An apron drafter as claimed in claim 1, in which the end portions of the front roll of the upper pair of horizontally spaced rolls is provided with a metal band about the periphery of the rubber cover for making contact with the front roll of the lower pair of horizontally spaced rolls.
 5. An apron drafter as claimed in claim 1, including crimping means for receiving the web discharged from the nip of said pair of front rolls, said crimping means comprising a pair of crimper rolls defining a nip therebetween and a stuffing box for receiving the web from the crimper rolls and discharging the same for coiling, said crimper rolls conveying the web at a linear speed faster than said pair of front rolls.
 6. An apron drafter as claimed in claim 5, in which said stuffing box includes a U-shaped channel member having side walls and a bottom wall and being opened at both ends, and an elongated tongue pivoted to the side walls at the upstream end thereof and having its free end bearing upon the web at the downstream end, said tongue being weighted at its downstream end whereby discharge of the web therefrom depends on force of the web entering the stuffing box by said pair of crimper rolls.
 7. An apron drafter for drafting a web of fibers into a homogeneous sliver comprising: 